Submitted to: American Society of Civil Engineers
Publication Type: Proceedings
Publication Acceptance Date: March 10, 1996
Publication Date: N/A
Interpretive Summary: Modification of subsurface drainage systems to restrict or stop flow is being proposed as an active method to manage shallow groundwater in arid areas. Successful management of shallow groundwater will contribute to a reduction in irrigation water requirements and improvement in the quality of surface water being used for drainage outflow. The modifications used in this experiment were the installation of butterfly valves on the drain laterals and weirs along the submain collector. The system was used during the production of tomato and cotton crops and resulted in reductions in applied irrigation water and drainage outflow. Reduced plant stress in the tomato crop resulted in improved yields in the area where the water table was closest to the surface. Variation in plant stress as a function of water table depth was observed in the tomato crop and not the cotton crop. These modifications show promise for wide application in arid irrigated areas where drainage water management is a problem.
Technical Abstract: A subsurface drainage system installed in a 50 ha field located on the west side of the San Joaquin Valley was modified to evaluate methods to manage shallow groundwater. The modifications included the installation of butterfly valves on the drainage laterals and the installation of weirs at three places along the submain collector. The effect of depth to water table on plant stress and yield was determined for three water table depth ranges in the field for both tomato and cotton crops. Increased stress was observed in the tomato plants with increasing depth to the water table, this was not observed in the cotton crop. Tomato yields were improved in areas with a water table at depths of 2.2 m or less compared to an area with the water table at a depth in excess of 2.2 m. The cotton yields were not affected by the depth to water table. The cotton yields were comparable to areas without shallow groundwater management. Total irrigation requirement was reduced in both the tomato and cotton crop. These modifications or something comparable have potential for wide application in irrigated areas with drainage water management problems.